Chemistry:Ligandrol

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Short description: Chemical compound
Ligandrol
LGD-4033.svg
Clinical data
Other namesVK5211; VK-5211; LGD-4033; LGD4033; Anabolicum
Routes of
administration		By mouth[1][2]
ATC code
  • None
Legal status
Legal status
Pharmacokinetic data
Elimination half-life24–36 hours[3][2][4]
Identifiers
CAS Number
PubChem CID
DrugBank
ChemSpider
UNII
ChEMBL
Chemical and physical data
FormulaC14H12F6N2O
Molar mass338.253 g·mol−1
3D model (JSmol)

Ligandrol, also known by the developmental code names VK5211 and LGD-4033, is a selective androgen receptor modulator (SARM) which is under development for the treatment of muscle atrophy in people with hip fracture.[5] It was also under development for the treatment of cachexia, hypogonadism, and osteoporosis, but development for these indications was discontinued.[5] Ligandrol has been reported to dose-dependently improve lean body mass and muscle strength in preliminary clinical trials, but is still being developed and has not been approved for medical use.[5][6][7][8] The drug is taken by mouth.[1][2]

Known possible side effects of ligandrol include headache, dry mouth, adverse lipid changes like decreased high-density lipoprotein (HDL) cholesterol levels, changes in sex hormone concentrations like decreased testosterone levels, elevated liver enzymes, and liver toxicity.[9][1][10][3][2][11][6] The potential of ligandrol and other SARMs for producing masculinization is largely uncharacterized and hence is unknown.[3] Ligandrol is a nonsteroidal SARM, acting as an agonist of the androgen receptor (AR), the biological target of androgens and anabolic steroids like testosterone and dihydrotestosterone (DHT).[10] However, it shows dissociation of effect between tissues in preclinical studies, with agonistic and anabolic effects in muscle and bone and partially agonistic or antagonistic effects in the prostate gland.[12][3][13]

Ligandrol was first described in 2010.[12][4] It is less clinically studied than other SARMs like enobosarm, with only a few small clinical trials having been conducted and reported.[14][11][9][2][8] Ligandrol has not yet completed clinical development or been approved for any use.[5][10][3] As of 2023, it is in phase 2 clinical trials for the treatment of hip fracture and muscle atrophy.[5] Ligandrol was developed by Ligand Pharmaceuticals, and is now being developed by Viking Therapeutics.[5]

Aside from its development as a potential pharmaceutical drug, ligandrol is on the World Anti-Doping Agency list of prohibited substances[15] and is sold for physique- and performance-enhancing purposes by black-market Internet suppliers.[3][9] Ligandrol is often used in these contexts at doses greatly exceeding those evaluated in clinical trials, with unknown effectiveness and safety.[3][9] Many products sold online that are purported to be ligandrol either contain none or contain other unrelated substances.[3][16] Social media has played an important role in facilitating the widespread non-medical use of SARMs.[17]


Medical uses

Ligandrol is not approved for any medical use and is not available as a licensed pharmaceutical drug as of 2023.[5][10][3]

Side effects

Side effects of ligandrol may include headache and dry mouth.[9] Ligandrol has been found to dose-dependently decrease levels of total testosterone, free testosterone, follicle-stimulating hormone (FSH), sex hormone-binding globulin (SHBG), HDL cholesterol, and triglycerides, while not affecting levels of luteinizing hormone (LH), total cholesterol, LDL cholesterol, or prostate-specific antigen (PSA).[3][2] Due to the decreased ratio of HDL cholesterol to LDL cholesterol, ligandrol could theoretically increase the risk of heart attack and stroke.[18]

Elevated liver enzymes, such as increased levels of aspartate aminotransferase (AST) or alanine aminotransferase (ALT), have not been reported with ligandrol in the few conducted clinical trials thus far.[6][9] However, multiple case reports of hepatotoxicity with ligandrol in the setting of non-medical use have been published.[11][6][9][19]

Ligandrol and other SARMs are largely uncharacterized in terms of their potential for masculinizing effects, for example in women.[3] In addition, the effects and safety of high doses of ligandrol and other SARMs, which are often used in non-medical contexts, are unknown.[3] Anecdotal reports of masculinization with black-market SARMs in women exist in online forums.[17]

The United States Food and Drug Administration (FDA) claims that "liver toxicity, adverse effects on blood lipid levels, and a potential to increase the risk of heart attack and stroke" are among the potential adverse health effects of SARMs including ligandrol.[20]

Overdose

Ligandrol has been assessed in clinical trials at single doses ranging from 0.1 to 22 mg and at repeated doses ranging from 0.1 to 2 mg/day for 3 to 12 weeks.[11] The drug sold via black-market Internet suppliers and used non-medically is often taken at much higher doses than those used in repeated-dose clinical trials (e.g., 5–10 mg/day), with unknown adverse effects and risks.[3][9][11]

Pharmacology

Pharmacodynamics

Ligandrol is a selective androgen receptor modulator (SARM), or a tissue-selective mixed agonist or partial agonist of the androgen receptor (AR).[10] This receptor is the biological target of endogenous androgens like testosterone and dihydrotestosterone (DHT) and of synthetic anabolic steroids like nandrolone and oxandrolone.[21][22][23] Ligandrol shows high affinity and selectivity for the AR, with an affinity (Ki) value of 0.9 nM.[12][3][13] It did not meaningfully interact with the progesterone receptor, glucocorticoid receptor, or mineralocorticoid receptor (all Ki > 4,000 nM), whereas the estrogen receptor α was not assessed.[13] In terms of in vitro transcriptional activity at the AR, the efficacy (Emax) of ligandrol was 132% to 133% and its EC50 was 3.6 to 4.4 nM.[12][13] The AR is widely expressed in tissues throughout the body, including in the prostate gland, seminal vesicles, genitals, gonads, skin, hair follicles, muscle, bone, heart, adrenal cortex, liver, kidneys, and brain, among others.[22][23] Ligandrol has been found to have varying full agonist and partial agonist AR-mediated effects in different tissues, including potent agonistic and anabolic activity in muscle and bone and weaker partial agonist activity in the prostate gland and sebaceous glands.[12][3][13][24][25]

Ligandrol has shown robust selectivity for stimulation of the levator ani muscle relative to stimulation of the prostate in rats.[12] At the highest assessed dose in castrated male rats, levator ani weight was increased to around 140% of that of gonadally intact controls, whereas prostate weight was only increased to around 45% of that of intact controls.[13] The tissue selectivity of ligandrol was independent of local tissue drug concentration, suggesting that its selectivity was intrinsic.[12][13] The muscle-stimulating effects of ligandrol have also been confirmed in humans in preliminary clinical trials.[10][26] The data also allow comparison between different SARMs and other AR agonists.[10][26] In a phase 1 clinical trial in 76 healthy young men, 1 mg/day ligandrol increased lean body mass by 1.2 kg after 3 weeks of treatment.[10][26][2] For comparison, enobosarm, another SARM, increased lean body mass by 1.3 kg at a dose of 3 mg/day after 12 weeks in healthy elderly men and postmenopausal women.[2][26][27] It was concluded that the employed dose of ligandrol produced similar increases in lean body mass compared to enobosarm despite a substantially shorter treatment period.[2] In a phase 2 clinical trial in 108 women and men with hip fracture, ligandrol increased lean body mass by 4.8% at 0.5 mg/day, 7.2% at 1 mg/day, and 9.1% at 2 mg/day after 12 weeks of treatment.[8] For comparison, lean body mass with enobosarm 3 mg/day after the same time period of 12 weeks increased by about 0.30% at 0.1 mg/day, 0.40% at 0.3 mg/day, 1.2% at 1 mg/day, and 3.1% at 3 mg/day, with only the latter change achieving statistical significance.[27] Relative to SARMs, supraphysiological doses of testosterone (300–600 mg/week intramuscular testosterone enanthate) over similar timeframes, like 20 weeks, have been found to result in lean body mass gains of 5 to 8 kg in healthy young men.[28][3][29]

In addition to selectivity for muscle and bone over the prostate gland, ligandrol has also been stated by Ligand Pharmaceuticals researchers to have reduced strength in the sebaceous glands.[12][4] Reduced activity in stimulating sebaceous gland formation, to about 30 to 50% of that produced by DHT at doses with similar anabolic potency in rats, has also been reported for certain other SARMs, like the steroidal agents TFM-4AS-1 and MK-0773.[12] In addition, enobosarm and MK-0773 have been reported to limitedly stimulate the sebaceous glands in small short-term clinical studies in women.[30][27][31]

Pharmacokinetics

Ligandrol showed linear or dose-proportional pharmacokinetics across doses of 0.1 to 1 mg/day over 21 days of administration.[2] Levels of ligandrol were 3-fold higher at day 21 compared to day 1, indicating significant accumulation with repeated administration.[2] The mean area-under-curve levels of ligandrol on day 21 were 19 ng•day/mL at 0.1 mg/day, 85 ng•day/mL at 0.3 mg/day, and 238 ng•day/mL at 1 mg/day.[2] The elimination half-life of ligandrol is 24 to 36 hours.[3][2][4] Pharmacokinetic studies of ligandrol for purposes of doping detection have also been conducted.[32][33][34][35]

Chemistry

Ligandrol is a nonsteroidal SARM with a pyrrolidinyl-benzonitrile core structure and is also referred to as a quinoline or quinolinone SARM.[3][12] LG121071 (LGD-121071), a tricyclic quinoline, was the predecessor compound of ligandrol.[10] The chemical structure of ligandrol had not been disclosed as late as 2013.[12][26] Ligandrol (LGD-4033) has sometimes been confused with other structurally related Ligand Pharmaceuticals SARMs including LGD-2226, LGD-2941, and LGD-3303,[10][5] but is a different compound from these agents.[12][10]

Ligandrol is a small-molecule (molecular weight = 338.3 g/mol) and highly lipophilic (predicted log P = 3.6–3.7) compound.[36][37]

History

The predecessor of ligandrol, LG121071 (LGD-121071), was discovered by Ligand Pharmaceuticals and was first described in the literature in January 1999.[10][38] It was the first orally active nonsteroidal androgen receptor agonist to be discovered.[39][38] LG121071 is a tricyclic quinoline derivative, and is structurally distinct from arylpropionamide SARMs like andarine and enobosarm (ostarine).[39] LGD-2226, a bicyclic quinoline SARM, was subsequently developed by Ligand Pharmaceuticals and TAP Pharmaceuticals in 2001.[39] Other quinoline SARMs, like LGD-2941 and LGD-3303, were also subsequently developed by Ligand Pharmaceuticals prior to the development of ligandrol (LGD-4033).[12][40]

Ligandrol was developed by Ligand Pharmaceuticals and was first described in the literature in 2010.[5][12][4] On the basis of a favorable preclinical profile, phase 1 clinical trials of ligandrol began in 2009.[12] The results of a single-dose phase 1 clinical trial were published as a conference abstract in 2010 and the findings of a multi-dose phase 1 trial were published as a journal article in 2013.[11][1][4][2] A third phase 1 trial was also conducted.[6][14] By 2012, a phase 2 trial of ligandrol for the treatment of muscle wasting related to cancer cachexia, acute rehabilitation (e.g., hip fracture), and acute illness was being prepared by Ligand Pharmaceuticals.[12][1] On 22 May 2014, Viking Therapeutics licensed the developmental rights of ligandrol from Ligand Pharmaceuticals and intended to advance the compound into mid-to-late-stage clinical trials.[10] The phase 2 study of ligandrol for muscle wasting was finally initiated in November 2016[41] and was completed with results reported in 2017 and 2018.[14][10][8] As of March 2023, ligandrol (VK5211) continues to be under development by Viking Therapeutics and continues to be in phase 2 clinical trials for treatment of muscle atrophy and hip fracture.[5]

Society and culture

Regulatory information

In the United States, ligandrol is an Investigational New Drug and is not approved for any medical use.[5]

Non-medical use

Though not an approved drug, ligandrol has been sold on the black market in countries where it is classified as an illegal substance.[42][43] Along with enobosarm (ostarine; GTx-024, S-22), andarine (GTx-007; S-4), and vosilasarm (RAD140; "testolone"), ligandrol is one of the most popular and common non-medically-used SARMs.[9][44] Many products sold online that are purported to be ligandrol either contain none or contain other unrelated substances, and doses are also frequently not as labeled.[3][16] Social media has played an important role in facilitating the widespread non-medical use of SARMs.[17]

On 23 October 2017, a nutritional supplement company in Missouri called Infantry Labs was warned by the FDA that the distribution of two of its products violated the Federal Food, Drug, and Cosmetic Act. One of the substances was ligandrol. The company advertised as benefits of the ligandrol: "increases in lean body mass and decrease in body fat" and "increases in strength, well being, as well as healing possibilities". The company mislabeled as "dietary supplements" what should have been "new drugs" or "prescription drugs" and were instructed to document the steps they would take in order to cease the violation.[20]

Also on 23 October 2017, the FDA sent a warning letter to a New Jersey company called Panther Sports Nutrition. The company's marketing approach for the product was similar to that of the Infantry Labs case, and the product was advertised as a "mass builder" and "physique enhancing agent".[45]

Doping in sport

Ligandrol is on the World Anti-Doping Association (WADA) list of prohibited drugs[15] and has been found in drug testing samples of some athletes.[46] Since at least June 2015, ligandrol has been available via the internet. In that month, German scientists proposed a new test to detect its metabolites present in human urine, and suggested an expansion of the WADA regime.[47] Ligandrol has been found in WADA samples and in racehorses as well.[48]

List of doping cases

Further information: List of doping in sport cases § Ligandrol

In 2015, the quarterback of the Florida Gators, Will Grier, was suspended for testing positive for ligandrol, a claim that the University of Florida denies.[49]

In 2017, Joakim Noah was banned for twenty games by the NBA for testing positive for ligandrol.[50]

In 2019, Australian swimmer Shayna Jack tested positive for ligandrol. She denies knowingly taking the substance.[51]

In August 2019, it came to light that Canadian sprint canoeist Laurence Vincent Lapointe tested positive for ligandrol; the athlete denies knowingly taking a forbidden substance that resulted in her suspension from competition. The athlete remarked that the National Team Training Centre purchased nutritional supplements for its athletes and denied buying or taking nutritional supplements on her own. [52] On January 27, 2020, she was cleared of all charges. The substance was found in her results because of an exchange of bodily fluids with her boyfriend, who took Ligandrol.[53]

In January 2020, Chilean ATP tennis singles competitor Nicolás Jarry tested positive for both ligandrol and stanozolol. He protested at the time that the multi-vitamins from Brazil that he took on the advice of an unnamed doctor were contaminated.[54]

On 3 September 2022, Nzubechi Grace Nwokocha was provisionally suspended for the use of banned substances [55][56] by the Athletics Integrity Unit (AIU).

On 23 January 2024, Tristan Thompson was suspended for 25 games by the NBA for testing positive for ibutamoren and Ligandrol.[57]

Research

Oral administration of ligandrol to cynomolgus monkeys at daily doses varying from 0 to 75 mg/kg over 13 weeks demonstrated significant body weight gain in both males and females. After 48 days, the 75 mg/kg dose testing was halted due to toxicity concerns, but this did not negatively impact development of the drug as this dose is significantly higher than the doses being utilized in a phase 2 clinical trial.[58]

Two phase 1 clinical trials of ligandrol have been conducted and reported.[11] The first was a single-dose study published as a conference abstract in 2010 and the second was a multi-dose study published as a journal article in 2013.[11][4][2] The multi-dose phase 1 trial published in 2013 reported that ligandrol dose-dependently improved lean body mass and muscle strength in 76 healthy young men over 21 days.[2] It was generally well-tolerated in this study, with no significant adverse effects reported.[2]

A phase 2 clinical trial, initiated on 3 November 2016, consisted of 108 women and men recovering from hip fracture surgery.[8] The randomized study participants received either placebo or varying doses of ligandrol over a period of 12 weeks, with improved lean body mass as the primary endpoint.[8] Other endpoints included satisfactory results in terms of quality of life, safety, and pharmacokinetics.[41] This study was completed and results reported in 2017 and 2018.[14][10][8] In the trial, ligandrol dose-dependently improved lean body mass and muscle strength and was reported to be safe and well-tolerated.[6][7][8] Placebo-adjusted lean body mass was increased by 4.8% at 0.5 mg/day, 7.2% at 1 mg/day, and 9.1% at 2 mg/day after 12 weeks.[8]

As of 2023, ligandrol has been less studied than other SARMs like enobosarm, with only three small phase 1 clinical trials and one phase 2 trial, or a total of four clinical studies, having been conducted and reported.[14][11][9][2][8]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 "Comparative safety evaluation of selective androgen receptor modulators and anabolic androgenic steroids". Expert Opin Drug Saf 14 (11): 1773–85. 2015. doi:10.1517/14740338.2015.1094052. PMID 26401842. 
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 "The safety, pharmacokinetics, and effects of LGD-4033, a novel nonsteroidal oral, selective androgen receptor modulator, in healthy young men". J Gerontol A Biol Sci Med Sci 68 (1): 87–95. January 2013. doi:10.1093/gerona/gls078. PMID 22459616. 
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 "Considerations, possible contraindications, and potential mechanisms for deleterious effect in recreational and athletic use of selective androgen receptor modulators (SARMs) in lieu of anabolic androgenic steroids: A narrative review". Steroids 164: 108753. December 2020. doi:10.1016/j.steroids.2020.108753. PMID 33148520. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 "P8-2-7 Phase I clinical trial of LGD-4033, a novel selective androgen receptor modulator (SARM)". Endocrine Journal 57 (Suppl 2 [14th International Congress of Endocrinology (ICE 2010), March 26-30, 2010, Kyoto, Japan]): S542. 2010. doi:10.1507/endocrj.57.S355. ISSN 0918-8959. https://www.jstage.jst.go.jp/article/endocrj/57/Suppl.2/57_57.S355/_pdf/-char/en#page=188. "LGD-4033 is a potent SARM that binds the human androgen receptor with Kd =0.9 nM. In animal models, it has anabolic effects on skeletal muscle and bone, but spares prostate, sebaceous glands, and female genitalia. In a double-blind, placebo-controlled, first-in-human Phase I trial, ascending single oral doses of LGD-4033 ranging from 0.1 mg to 22 mg were administered to healthy males. LGD4033 was safe and well tolerated up to the highest tested dose with no serious adverse events reported. LGD-4033 exhibited dose-proportional, sustained systemic exposure (AUC0-48hr: 24 to 7000 ng. hr/ mL for 0.1 and 22 mg doses, respectively). The elimination half-life (t1/2) was 31 hrs, indicating LGD-4033 is amenable for once daily dosing. PK-PD studies were conducted in orchiectomized (ORDX) rats, a model of androgen action, to determine the LGD-4033 efficacious exposure level. Subcutaneous minipumps were used to mimic the 10-fold longer t1/2 in humans vs. rats. A dose that produced an AUC of 80 ng. hr/mL restored the atrophied muscle mass of ORDX rats to the eugonadal level (270% increase in levator ani muscle weight with LGD-4033 vs. vehicle) and reduced the elevated luteinizing hormone level of ORDX rats by 98%. The efficacious range predicted by the preclinical model will be achieved by repeated daily doses ca. 0.25 mg in humans. Conclusion: LGD-4033 is a well-tolerated and highly tissue-specific, potential new treatment for sarcopenia (e.g., cancer cachexia or the frail elderly) and osteoporosis that is predicted to be effective using low, daily oral doses. A Phase I multi-dose study is in progress.". 
  5. ↑ 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 "VK 5211 - AdisInsight". https://adisinsight.springer.com/drugs/800030373. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 "Selective Androgen Receptor Modulators: An Emerging Liver Toxin". J Clin Transl Hepatol 11 (1): 188–196. February 2023. PMID 36479151. 
  7. ↑ 7.0 7.1 Girgis, Christian M. (2019). "Sex Steroid Hormones and Osteosarcopenia". Osteosarcopenia: Bone, Muscle and Fat Interactions. Cham: Springer International Publishing. pp. 173–190. doi:10.1007/978-3-030-25890-0_8. ISBN 978-3-030-25889-4. "Other molecules have been developed including LGD-4033 which increased muscle mass and strength in healthy males after 3 weeks (Basaria et al. 2013) [...] Recently, a phase 2 trial on the agent VK211 demonstrated dose-dependent increases in lean body mass, and improvements in physical performance in patients who had sustained hip fracture (Ristic et al. 2018). Whilst SARMs hold great promise as anabolic agents that may offer an effective therapy for osteosarcopenia, long-term side effects of these agents are unknown, studies are generally small and of short duration. Regulation of these products poses immense challenges with their high uptake on the black market and via the internet as performance-enhancing, body-building agents, which may overshadow their potential mainstream application in disorders of aging." 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 8.7 8.8 8.9 "1072 VK5211, a novel selective androgen receptor modulator (SARM), significantly improves lean body mass in hip fracture patients: results of a 12 week phase 2 trial". Journal of Bone and Mineral Research 33 (Suppl 1 [2018 Annual Meeting of the American Society for Bone and Mineral Research Palais des congrès de Montréal in Montréal, Quebéc, Canada September 28 – October 1, 2018]): S24. 2018. doi:10.1002/jbmr.3621. PMID 30444937. https://asbmr.onlinelibrary.wiley.com/doi/pdf/10.1002/jbmr.3621#page=38. "Introduction Hip fractures are a leading cause of disability and morbidity in older people. Post-facture, an increased catabolic state often leads to loss of muscle, which can impair balance and endurance, potentially increasing the risk of further injury. Anabolic steroids have been shown to improve muscle mass in certain settings. Selective androgen receptor modulators (SARMs) could be similarly effective in older patients who have suffered muscle loss following hip fracture, while potentially avoiding undesired side effects associated with broad-acting anabolic agents. VK5211 is a novel, non-steroidal, orally available SARM that has been shown to improve muscle mass and bone mineral density in animal models. In humans, a prior Phase 1 study demonstrated increases in lean body mass after 21 days of dosing. Purpose A 12 week study was conducted to assess the safety and efficacy of VK5211 in patients who had suffered a hip fracture. Methods A randomized, double-blind, placebo-controlled, multicenter, international Phase 2 trial was conducted to evaluate VK5211 in patients recovering from hip fracture. Patients were randomized to receive daily oral VK5211 doses of 0.5 mg, 1.0 mg, 2.0 mg, or placebo, for 12 weeks. The primary endpoint evaluated change from baseline in lean body mass, less head, in patients receiving VK5211 compared with placebo. Secondary and exploratory endpoints included changes in appendicular lean mass, bone density, and functional performance. Results A total of 108 patients were randomized (83 F, 25 M; mean age 77). Patients receiving VK5211 demonstrated significant increases in lean body mass, less head, after 12 weeks. Placebo-adjusted increases were 4.8% at 0.5 mg, 7.2% at 1.0 mg, and 9.1% at 2.0 mg (p < 0.005 for each). The proportions of patients experiencing at least a 2.0 kg increase were 14% with placebo, 57% at 0.5 mg, 65% at 1.0 mg, and 81% at 2.0 mg (p < 0.01 for each). Patients receiving VK5211 demonstrated improvement in certain measures of functional performance, including the 6-minute walk test and short physical performance battery (these endpoints were not powered for significance). The rates of adverse events were similar in cohorts receiving VK5211 as compared with placebo, and no drug-related SAEs were observed in VK5211-treated patients. Conclusion VK5211 was well-tolerated and produced improvements in lean body mass in hip fracture patients following 12 weeks of dosing. Further evaluation in this setting is warranted.". 
  9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 9.6 9.7 9.8 9.9 "Androgen Receptor and Cardiovascular Disease: A Potential Risk for the Abuse of Supplements Containing Selective Androgen Receptor Modulators". Nutrients 15 (15): 3330. July 2023. doi:10.3390/nu15153330. PMID 37571268. 
  10. ↑ 10.00 10.01 10.02 10.03 10.04 10.05 10.06 10.07 10.08 10.09 10.10 10.11 10.12 10.13 10.14 "Selective androgen receptor modulators (SARMs) as pharmacological treatment for muscle wasting in ongoing clinical trials". Expert Opin Investig Drugs 29 (8): 881–891. August 2020. doi:10.1080/13543784.2020.1777275. PMID 32476495. 
  11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 "Systematic Review of Safety of Selective Androgen Receptor Modulators in Healthy Adults: Implications for Recreational Users". J Xenobiot 13 (2): 218–236. May 2023. doi:10.3390/jox13020017. PMID 37218811. 
  12. ↑ 12.00 12.01 12.02 12.03 12.04 12.05 12.06 12.07 12.08 12.09 12.10 12.11 12.12 12.13 12.14 12.15 "Deciphering the selective androgen receptor modulators paradigm". Expert Opin Drug Discov 8 (2): 191–218. February 2013. doi:10.1517/17460441.2013.741582. PMID 23231475. 
  13. ↑ 13.0 13.1 13.2 13.3 13.4 13.5 13.6 "LGD-4033 builds muscle and bone with reduced prostate activity and may be beneficial in age-related frailty", Proceedings of the 62nd Annual Meeting of the Gerontology Society of America, November 11-21, 2009, Atlanta, Georgia, 2009, https://vikingtherapeutics.com/wp-content/uploads/Vajda-SARM-Builds-Muscle-and-Bone-with-Reduced-Prostate-Activity-Poster-Gerontology-Soc.-2009.pdf 
  14. ↑ 14.0 14.1 14.2 14.3 14.4 "VK5211". https://vikingtherapeutics.com/pipeline/other-pipeline-programs/vk5211/. 
  15. ↑ 15.0 15.1 "Prohibited List". World Anti Doping Agency. 2014-07-22. https://www.wada-ama.org/en/resources/science-medicine/prohibited-list-documents. 
  16. ↑ 16.0 16.1 "Chemical Composition and Labeling of Substances Marketed as Selective Androgen Receptor Modulators and Sold via the Internet". JAMA 318 (20): 2004–2010. November 2017. doi:10.1001/jama.2017.17069. PMID 29183075. 
  17. ↑ 17.0 17.1 17.2 "Social media's impact on widespread SARMs abuse". Phys Sportsmed 51 (4): 291–293. August 2023. doi:10.1080/00913847.2022.2078679. PMID 35574698. 
  18. ↑ "Medicinal Use of Testosterone and Related Steroids Revisited". Molecules 26 (4): 1032. February 2021. doi:10.3390/molecules26041032. PMID 33672087. 
  19. ↑ "Selective androgen receptor modulator use and related adverse events including drug-induced liver injury: Analysis of suspected cases". Eur J Clin Pharmacol. December 2023. doi:10.1007/s00228-023-03592-3. PMID 38059982. 
  20. ↑ 20.0 20.1 "WARNING LETTER Infantry Labs LLC MARCS-CMS 535333 — OCT 23, 2017". FDA. 23 October 2017. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/infantry-labs-llc-535333-10232017. 
  21. ↑ "Novel Uses for the Anabolic Androgenic Steroids Nandrolone and Oxandrolone in the Management of Male Health". Curr Urol Rep 17 (10): 72. October 2016. doi:10.1007/s11934-016-0629-8. PMID 27535042. 
  22. ↑ 22.0 22.1 "Nonsteroidal tissue selective androgen receptor modulators: a promising class of clinical candidates". Expert Opinion on Therapeutic Patents (Informa Healthcare) 15 (11): 1565–1585. 2005-10-28. doi:10.1517/13543776.15.11.1565. ISSN 1354-3776. 
  23. ↑ 23.0 23.1 "Pharmacology of anabolic steroids". Br J Pharmacol 154 (3): 502–21. June 2008. doi:10.1038/bjp.2008.165. PMID 18500378. 
  24. ↑ "Ostarine and Ligandrol Improve Muscle Tissue in an Ovariectomized Rat Model". Front Endocrinol (Lausanne) 11: 556581. 2020. doi:10.3389/fendo.2020.556581. PMID 33042018. 
  25. ↑ "Effects of ligandrol as a selective androgen receptor modulator in a rat model for osteoporosis". J Bone Miner Metab 41 (6): 741–751. November 2023. doi:10.1007/s00774-023-01453-8. PMID 37407738. 
  26. ↑ 26.0 26.1 26.2 26.3 26.4 "Selective androgen receptor modulators for the prevention and treatment of muscle wasting associated with cancer". Curr Opin Support Palliat Care 7 (4): 345–51. December 2013. doi:10.1097/SPC.0000000000000015. PMID 24189892. 
  27. ↑ 27.0 27.1 27.2 "The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II trial". J Cachexia Sarcopenia Muscle 2 (3): 153–161. September 2011. doi:10.1007/s13539-011-0034-6. PMID 22031847. 
  28. ↑ "Selective androgen receptor modulators as function promoting therapies". Current Opinion in Clinical Nutrition and Metabolic Care 12 (3): 232–240. May 2009. doi:10.1097/MCO.0b013e32832a3d79. PMID 19357508. "At the doses that have been tested, the first generation SARMs induce modest gains in lean body mass in healthy volunteers, which are nowhere near the much greater gains in skeletal muscle mass reported with supraphysiological doses of testosterone. The modest gains of 1.0 to 1.5 kg in fat-free mass with first generation SARMs over 4–6 weeks should be contrasted with the 5–7 kg gains in fat-free mass with 300 and 600 mg doses of testosterone enanthate. However, it is possible that next generation of SARM molecules will have greater potency and selectivity than the first generation SARMs.". 
  29. ↑ "Testosterone dose-response relationships in healthy young men". American Journal of Physiology. Endocrinology and Metabolism 281 (6): E1172–E1181. December 2001. doi:10.1152/ajpendo.2001.281.6.E1172. PMID 11701431. "The administration of the GnRH agonist plus graded doses of testosterone resulted in mean nadir testosterone concentrations of 253, 306, 542, 1,345, and 2,370 ng/dl at the 25-, 50-, 125-, 300-, and 600-mg doses, respectively. Fat-free mass increased dose dependently in men receiving 125, 300, or 600 mg of testosterone weekly (change +3.4, 5.2, and 7.9 kg, respectively). The changes in fat-free mass were highly dependent on testosterone dose (P = 0.0001) and correlated with log testosterone concentrations (r = 0.73, P = 0.0001).". 
  30. ↑ "Selective androgen receptor modulators as improved androgen therapy for advanced breast cancer". Steroids 90: 94–100. November 2014. doi:10.1016/j.steroids.2014.06.010. PMID 24945109. 
  31. ↑ "Discovery of the selective androgen receptor modulator MK-0773 using a rational development strategy based on differential transcriptional requirements for androgenic anabolism versus reproductive physiology". J Biol Chem 285 (22): 17054–64. May 2010. doi:10.1074/jbc.M109.099002. PMID 20356837. 
  32. ↑ "Investigations into the elimination profiles and metabolite ratios of micro-dosed selective androgen receptor modulator LGD-4033 for doping control purposes". Anal Bioanal Chem 414 (2): 1151–1162. January 2022. doi:10.1007/s00216-021-03740-7. PMID 34734312. 
  33. ↑ "Human in vivo metabolism study of LGD-4033". Drug Test Anal 10 (11–12): 1635–1645. November 2018. doi:10.1002/dta.2512. PMID 30255601. 
  34. ↑ "In vitro metabolism study of a black market product containing SARM LGD-4033". Drug Test Anal 9 (2): 168–178. February 2017. doi:10.1002/dta.1930. PMID 26767942. 
  35. ↑ "Detection of LGD-4033 and its metabolites in athlete urine samples". Drug Test Anal 9 (1): 127–134. January 2017. doi:10.1002/dta.1986. PMID 27168428. 
  36. ↑ "Ligandrol". https://pubchem.ncbi.nlm.nih.gov/compound/Ligandrol. 
  37. ↑ "Ligandrol". https://go.drugbank.com/drugs/DB13934. 
  38. ↑ 38.0 38.1 "Discovery of a potent, orally active, nonsteroidal androgen receptor agonist: 4-ethyl-1,2,3,4-tetrahydro-6- (trifluoromethyl)-8-pyridono[5,6-g]- quinoline (LG121071)". J Med Chem 42 (2): 210–2. January 1999. doi:10.1021/jm9806648. PMID 9925725. 
  39. ↑ 39.0 39.1 39.2 "Pharmacokinetics and pharmacodynamics of nonsteroidal androgen receptor ligands". Pharm Res 23 (8): 1641–58. August 2006. doi:10.1007/s11095-006-9024-3. PMID 16841196. 
  40. ↑ Jasuja, Ravi; Zacharov, Mikhail N.; Bhasin, Shalender (26 July 2012). "The state-of-the-art in the development of selective androgen receptor modulators". Testosterone. Cambridge University Press. pp. 459–469. doi:10.1017/cbo9781139003353.022. ISBN 978-1-139-00335-3. 
  41. ↑ 41.0 41.1 "Viking Therapeutics Initiates Phase 2 Trial of VK5211 in Patients Recovering From Hip Fracture.". FierceBiotech. Questex LLC. 21 November 2016. https://www.fiercebiotech.com/biotech/viking-therapeutics-initiates-phase-2-trial-of-vk5211-patients-recovering-from-hip-fracture. 
  42. ↑ "In vitro metabolism study of a black market product containing SARM LGD-4033". Drug Testing and Analysis 9 (2): 168–178. February 2017. doi:10.1002/dta.1930. PMID 26767942. 
  43. ↑ "Identification of black market products and potential doping agents in Germany 2010-2013". European Journal of Clinical Pharmacology 70 (11): 1303–1311. November 2014. doi:10.1007/s00228-014-1743-5. PMID 25168622. 
  44. ↑ Hahamyan, Henrik; Gould, Heath; Gregory, Andrew; Dodson, Christopher; Gausden, Elizabeth; Voos, James; Calcei, Jacob; Vasireddi, Nikhil (2023-07-01). "Poster 390: Systematic Review of SARMs Abuse in Athletes". Orthopaedic Journal of Sports Medicine 11 (7_suppl3). doi:10.1177/2325967123S00352. ISSN 2325-9671. 
  45. ↑ "WARNING LETTER Panther Sports Nutrition MARCS-CMS 535341 — OCT 23, 2017". FDA. 23 October 2017. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/panther-sports-nutrition-535341-10232017. 
  46. ↑ "Detection of LGD-4033 and its metabolites in athlete urine samples". Drug Testing and Analysis 9 (1): 127–134. January 2017. doi:10.1002/dta.1986. PMID 27168428. 
  47. ↑ "Characterization of a non-approved selective androgen receptor modulator drug candidate sold via the Internet and identification of in vitro generated phase-I metabolites for human sports drug testing". Rapid Communications in Mass Spectrometry 29 (11): 991–999. June 2015. doi:10.1002/rcm.7189. PMID 26044265. Bibcode: 2015RCMS...29..991T. 
  48. ↑ "Equine in vivo-derived metabolites of the SARM LGD-4033 and comparison with human and fungal metabolites". Journal of Chromatography. B, Analytical Technologies in the Biomedical and Life Sciences 1074-1075: 91–98. February 2018. doi:10.1016/j.jchromb.2017.12.010. PMID 29334634. 
  49. ↑ "Florida starting QB Will Grier suspended for at least 2015 after taking banned substance.". SB Nation. 12 October 2015. https://www.sbnation.com/college-football/2015/10/12/9510055/florida-qb-will-grier-suspended-for-rest-of-2015-due-to-ncaa. 
  50. ↑ "NBA bans Joakim Noah 20 games for drug violation". Fox Sports. March 25, 2017. https://www.foxsports.com/ba/story/nba-bans-joakim-noah-20-games-for-drug-violation-032517. 
  51. ↑ "Shayna Jack reveals banned substance Ligandrol was behind her doping suspension from swimming". Australian Broadcasting Corporation. July 28, 2019. https://www.abc.net.au/news/2019-07-28/shayna-jack-reveals-banned-substance-ligandrol/11354742. 
  52. ↑ "Canada's Vincent Lapointe reveals she tested positive for muscle-building substance". CBC. 20 August 2019. https://www.cbc.ca/sports/olympics/canoe-kayak/laurence-vincent-lapointe-positive-test-banned-substance-1.5253029. 
  53. ↑ "Dopage : Laurence Vincent Lapointe blanchie et soulagée" (in French). Radio Canada. 27 January 2020. https://ici.radio-canada.ca/sports/1492442/dopage-levee-suspension-laurence-vincent-lapointe-canoe-ligandrol. 
  54. ↑ "Wimbledon doubles champion Robert Farah fails drugs test". Telegraph Media Group Limited. 15 January 2020. https://www.telegraph.co.uk/tennis/2020/01/14/wimbledon-doubles-champion-robert-farah-fails-drugs-test/. 
  55. ↑ Ostarine and Ligandrol
  56. ↑ "Commonwealth gold medallist Nwokocha provisionally suspended for doping" (in en). Reuters. 2022-09-03. https://www.reuters.com/lifestyle/sports/commonwealth-gold-medallist-nwokocha-provisionally-suspended-doping-2022-09-03/. 
  57. ↑ "Cavs' Tristan Thompson suspended 25 games without pay by NBA". National Basketball Association. January 23, 2024. https://www.nba.com/news/tristan-thompson-suspended-25-games. 
  58. ↑ "VKTX: Additional Preclinical Data Shows Robust and Durable Weight Gain for VK5211-Treated Primates.". Yahoo. Yahoo, Inc.. 21 November 2016. https://finance.yahoo.com/news/vktx-additional-preclinical-data-shows-153000687.html?guccounter=1&guce_referrer=aHR0cHM6Ly93d3cuZ29vZ2xlLmNvbS8&guce_referrer_sig=AQAAAB6OAsGUrYy_-5vcDqTR0S0dZnvU-acaGigUYB81DDY5o5fc6TnudFwYfjnfPP3kqLz1Z1BgQpAITksjtbbnfy0Uca7ROXl7BwcYbmM9XbsVhUixDnWIFeVFgkmm30ISY2QX4JC_x_9hwl--EJclvfmpL297ceWKjO_WIdBeddKJ. 

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